The present disclosure relates to a sheet feeder for feeding a sheet in a predetermined sheet feeding direction and an image forming apparatus to which the sheet feeder is applied.
An image forming apparatus such as a copier or a printer includes a sheet cassette (sheet feeder) for storing sheets to which an image is to be transferred. This sheet cassette is provided with a pair of side guides which are slid according to the size of stored sheets and guide lateral sides of the sheets. One and the other of the side guides are moved in conjunction with each other by an interlocking mechanism including rack members and a pinion gear.
There is known a detection technology for automatically detecting the size of sheets stored in a sheet cassette by assembling a sensor member with a pinion gear. A variable resistor with a movable electrode is generally used as the sensor member and a rotary shaft of the pinion gear is coupled to the movable electrode. The movable electrode is rotated by the rotation of the pinion gear associated with sliding movements of side guides, whereby a resistance value of the variable resistor changes. By monitoring this change of the resistance value, the size of the stored sheets is discriminated.